[SM7622]
good reading -but might as well keep eating too! -as long as 'rome is burning'! :-)

perryb
Australia's aborigines -Hard paternalism and Dammed if they do -Dolphins, catfish and people at risk

Prince charming at the Roosevelt

Heading for Hills May Be Only Option on Fiji

(two short items) Forecasting Global Warming's Monumental Impact and Trace amounts of cocaine are wafting through the air in some cities...

The Cult of the Amateur by Andrew Keen -LATIMES book review followed by NPR interview with the author

Science 22 June 2007: Science Magazine
News Focus
AQUATIC ECOLOGY:
The Last of the Leviathans

Richard Stone

A young biologist is teaming up with colleagues on six continents to document the world's biggest freshwater fishes--and, he hopes, help avert an extinction crisis


Figure 1 Moby Dick of the Mekong. Caught in 2005, this record giant catfish weighed 293 kilograms.
CREDIT: SUTHEP KRITSANAVARIN

CHIANG KHONG, THAILAND--Eddies and whirlpools, weak and evanescent, swirl water the color of milk chocolate in a narrow stretch of the Mekong River between Laos and Thailand. Zeb Hogan asks the longboat driver to steer toward a rocky island. As slate-gray thunderclouds bear down from the north, the boat eases alongside a small bamboo raft roped to shore in a tiny cove.
   Hogan leans out and flips the raft over. Fixed underneath is a metal cylinder that holds an acoustic receiver. Hogan, a fisheries biologist with the University of Nevada, Reno, is checking to see if this and 16 other receivers along a 400-kilometer stretch of the river are ready for showtime. On 6 May, near Chiang Khong, he stuck an acoustic transmitter on the dorsal fin of a Mekong giant catfish. It was the only one caught this year, and the first ever tagged successfully, in Thailand. The receivers will track its movements. "We think this part of the Mekong is critical habitat," Hogan says. "Somewhere around here is the spawning area."
   But even after a decade of reconnaissance in the Golden Triangle, the highlands where Laos, Myanmar, and Thailand meet, Hogan is not quite sure where that area is. The only certainty is that the giant catfish (Pangasianodon gigas), one of the world's biggest freshwater fishes, is getting harder to catch. Hogan has a finger on the fading pulse of other Mekong monsters as well, including the giant pangasius (Pangasius sanitwongsei) and the giant freshwater stingray (Himantura chaophraya), both of which rival the giant catfish in sheer heft and which are also at risk.
   Backed by the National Geographic Society (NGS), Hogan this spring has embarked on a 3-year "Megafishes Project" to document and protect the titans of the world's rivers and lakes: two-dozen-odd freshwater fishes that can top 200 pounds or 6 feet long (91 kilograms or 183 centimeters; see table). Many of these sumo-sized species are on the ropes, pummeled by overfishing and habitat degradation. Hogan's quest has begun on the Mekong, whose 1200-plus fish species make it the world's most biologically diverse river basin of this size. The Mekong is in the grip of a global calamity unfolding in fresh water, which accounts for 0.01% of all the planet's water but is home to at least 10,000, or about 40%, of known fish species. "Everywhere we look, the largest fish are disappearing," Hogan says. "These are iconic fish," adds environmental scientist Thomas Lovejoy, president of the Heinz Center in Washington, D.C. "Much like tigers on land, they are flagship species representing the wonders of life in rivers."
   Lovejoy and others laud Hogan for sounding the alarm. The "freshwater extinction crisis" deserves more attention, says Julian Olden, an aquatic ecologist at the University of Washington (UW), Seattle. Megafishes, adds Peter McIntyre, a fish biologist at Wright State University in Dayton, Ohio, "are emblematic of the problems of overexploitation and habitat alteration facing freshwater fishes around the world." By stirring up interest in the megafishes, Hogan "is likely to benefit numerous other species," McIntyre says.
   Large freshwater fish "are uniquely vulnerable," says David Dudgeon, an aquatic ecologist at the University of Hong Kong. They can live for decades, and "an awful lot of bad things can happen before they mature," he says. The consequences are particularly devastating for species confined to a single river. "If you screw up that habitat, they're gone," Dudgeon says.
   Unlike pandas, their cuddly appeal is nil. "People have a hard time sympathizing with fish," acknowledges Hogan. But when it comes to freshwater creatures, these "are the largest ones out there, and they're in big trouble."

Trophy fish evangelism
Last year, when a lengthy search for the baiji, or Yangtze River dolphin, came up empty, Hogan viewed the mammal's disappearance as an ominous portent. The Chinese team had anticipated a diminished population, not a total wipeout (Science, 22 December 2006, p. 1860). Similarly, Hogan fears that the Mekong River's giant pangasius is well on the way to oblivion. Unlike the giant catfish--a bottom feeder--the giant pangasius, also called the dog-eating catfish, is a predator. (Fishers snared it years ago by baiting hooks with dog flesh.) "The most common reaction I get is surprise that these species exist," says Hogan. By the end of World War II, pangasius specimens larger than 2 meters were rare in Thailand, and it may be extirpated from one of its original haunts, Thailand's Chao Phraya River. Now it's fighting a losing battle in the Mekong. "People aren't catching big ones anymore," Hogan says. The giant pangasius might disappear before basic sleuthing can be done, he says: "We know almost nothing about it."
   Information is scarce--and time is running out--for most species on the megafish list. Take the arapaima, or pirarucu, a South American fish that must surface every 15 minutes or so to gulp air. The biggest arapaima (Arapaima gigas) topped 3 meters and 200 kilograms at one time. But their need to breathe makes them easy to harpoon. In recent decades, the average capture size has "drastically decreased," says arapaima expert Patricia Pinho of the University of California, Davis.
   Like the giant pangasius, certain arapaima varieties may vanish before scientists become acquainted with them. Some species have not yet been described, whereas others have not been seen since the 1800s, says Donald Stewart, a fish biologist at the State University of New York (SUNY) College of Environmental Science and Forestry in Syracuse. He and his graduate students are studying arapaima in Brazil and Guyana. "Insufficient knowledge of the taxonomy and ecology" impedes conservation, says Stewart. "The first, last, and only meaningful analysis of species-level taxonomy for arapaima was in 1847!"
   The geography of human development could doom the megafishes. "In contrast to big sea dwellers, these riverine giants often live in close contact with dense human populations," says Stewart. In the Mekong, Amazon, and other river basins in the developing world, fishery interests usually trump preservation.
   


Figure 3 Lassoed. This giant freshwater stingray measured 2 meters in width and 4 meters from stem to stern; fishers claim to have seen stingrays twice that size.
CREDIT: COURTESY OF ZEB HOGAN

Dams, industrial effluents, and commercial navigation add to the pressure. "Freshwater systems get it every which way. It's hard to find a big river that hasn't been massively modified," says conservation ecologist Stuart Pimm of Duke University in Durham, North Carolina. An extreme case is the Yangtze, where a triple whammy of habitat modification, pollution, and heavy boat traffic may have turned the Chinese paddlefish (Psephurus gladius) into "the living dead," in that although individuals may still ply the river, the species itself could be doomed, says Dudgeon. The fish may be past the point of no return, he explains: Not even habitat preservation might save it now. "I've been searching since 2003 in almost all the Yangtze and have found none," says Wei Qiwei of the Yangtze River Fisheries Research Institute in Jingzhou.
   Because many megafishes are migratory, "large dams are a huge threat," says Ian Baird, a geographer at the University of British Columbia (UBC) in Vancouver who works on the Mekong. Scientists and activists are up in arms over the Laotian government's plans to build the first hydroelectric dam on the Mekong south of China, at Siphandone near the Laos-Cambodia border. The dam would block a channel that migratory fish, such as giant catfish, use to bypass the Khone Falls, says Roger Mollot, a fisheries expert with the World Wide Fund for Nature (WWF) in Vientiane, Laos. That prospect, he says, "is obviously a major concern for fish biodiversity and fishing livelihoods."
   This is not the sole menace in one of the most productive fisheries in the world. The Mekong Navigation Improvement Project intends to dynamite and dredge a stretch of the river north of Chiang Khong. "They're considering blasting in the presumed spawning grounds of the giant catfish," says Hogan. Dudgeon feels that blasting there "could be the last nail in the coffin for the species." Fortuitously, the work has been postponed out of national security concerns, explains Mollot: "The Thai government worries that blasting will alter the hydrology of the river," which, in that stretch, forms part of the Thai-Laos border.
   Thanks to quirks of topography or, rarely, sound management, a few megafishes are holding their own. Although subjected to intensive fishing, the giant perch (Lates angustifrons) in central Africa's Lake Tanganyika is lucky "in that it has a huge, deep lake to hide in and relatively low-technology fisheries methods to contend with," says McIntyre. "Their populations may well persist in the lake's depths despite the heavy fishing pressure." And in North America, the lake sturgeon (Acipenser fulvescens), decimated by anglers early in the 20th century, has rebounded. "They are relatively well-managed, and their populations remain stable," says Jake Vander Zanden, an aquatic ecologist at the University of Wisconsin, Madison. "There are important lessons in the success stories."

[THE MEGA 20: THE WORLD'S LARGEST FRESHWATER FISH](*1)

In many regions, however, conservation and science are far down the list of priorities. "There hasn't been a lot of emphasis on research," says Hogan. "There just aren't that many people doing this kind of work." And environmental protection is a novel concept in the Mekong River Basin. "Frankly, most of us are only beginning to learn about conservation," says Uthairat Na-Nakorn, a fish geneticist at Kasetsart University in Bangkok. In Thailand, she says, "when an outsider raises an issue, the issue becomes more important."
   That's where Hogan is making a mark.
   Hogan, 33, says his megafish epiphany came 10 years ago, when he spent the 1996-97 academic year on a Fulbright student fellowship at Thailand's Chiang Mai University. "I came to Thailand at a very good time," he says. Interest in Mekong ecology was waxing as a result of a major study into how future dams could harm the lower Mekong. After learning Thai, Hogan visited village markets to record the kinds of fish for sale. He narrowed his focus to the pangasiids, a group of migratory Mekong catfishes that spawn in spring, at the start of the rainy season. Hogan and colleagues determined that the silver-toned catfish (P. krempfi), unlike its cousins, is anadromous: It's a saltwater species that enters the river only to spawn. They nailed this from the high strontium levels in the catfish's otoliths, or ear stones, and an isotopic signature in muscle tissue indicative of growth in a marine environment, the South China Sea.
   Hogan says his seduction by the Mekong giant catfish "happened by accident," after he had begun doctoral ecology studies at the University of California, Davis. In April 2001, he went to Chiang Khong for the annual hunt of pla beuk, or buffalo fish, as the giant catfish is called in Thailand. A century ago, fishers hauled in hundreds per year. By the time Hogan arrived on the scene, he says, "it was the end of the heyday."
   Fishers in the Chiang Khong area had landed 20 in 1999. Hogan hung around Chiang Khong for 1 month in 2001, but no giant catfish were netted. The same thing--nothing--happened in 2002 and 2003. "There was a feeling, 'Hold on, we may have a problem here,' " Hogan says. There was a small rebound in 2004 and 2005, when seven and four, respectively, were caught. Then only one was netted by Laotian fishers last year, and the one this year that was tagged. Several giant catfish each year continue to be captured, and usually released, in the Tonlé Sap region of Cambodia, where the fish rears its young after spawning. The statistics are grim, and the ecological forces behind the year-toyear fluctuations upstream are a mystery. "No one really knows what's happening in the river," Hogan says.
   


Figure 5 Goliaths of the Amazon. Protecting megafishes will require more research and in some cases litigation, says Donald Stewart, seen here with arapaima harvested by fishers in Brazil's Mamirauá Reserve.
CREDIT: L. CASTELLO

Big-game hunting
On the beach on the Laotian side of the Mekong, across from Chiang Khong, several Thai fishers are lounging beneath a roof thatched with palm leaves. Their fraternity holds exclusive fishing rights for the giant catfish. In Thailand, only residents of Hat Khrai, a village next to Chiang Khong, can claim that honor, which has passed from father to son for generations. In recent years, the season has been limited to 1 week per year.
   This May, after a voluntary moratorium in 2006, members of the Hat Khrai Mekong Giant Catfish Club are anticipating a return to the hunt. The thick-twine gill nets, deployed exclusively for the giant catfish, are laid neatly in a few of the longboats tied to shore. The fishers, languid in the midday heat and eyes rheumy from homebrewed rice whiskey, are planning to hit the river in the evening. A short walk down the beach, a few of their sons are sprawled out under a tarp. The rainy season descended a month early, and with a squall approaching, the young men are about to get drenched. "The catfish are coming," one says, prophetically. He's worth heeding: In 2005, he and two friends landed the world-record giant catfish, a 2.7-meter- long, grizzly bear-sized titan that weighed 293 kilograms. With catches since then so rare, that specimen may well have been the last of the leviathans.
   This season, the fishing is strictly for scientific purposes; any giant catfish snared must be tagged and released in return for cash. For the giant catfish tagged on 6 May, Hogan and a documentary film crew forked over the equivalent of $1500, roughly market value. The meat, a delicacy in Thailand, fetches up to $15 per kilogram. "Thai people think that eating it will give them good luck forever," says Sujin Nukwan, director of the Inland Aquaculture Research Institute in Ayutthaya, Thailand. Hogan tried it a few years ago. "It tastes muddy," he says.
   The older fishers are an invaluable historical resource for Hogan. So far, he has interviewed 60 fishers over the age of 40, asking them, among other things, to compare average catch and size now compared with 20 years ago--standard World Conservation Union criteria for assessing fish stocks. The fishers also lend a hand with tracking tagged fish. "For each receiver, there's a fisherman responsible," Hogan says. "Our ultimate goal is to nail down where the Mekong giant catfish is spawning."
   After finishing his work at Chiang Khong, Hogan traveled down the Mekong to Cambodia, film crew in tow, to look for a giant stingray, which reportedly can reach 500 kilograms or more. "Cambodia is the last refuge for some of these species," he says. Fishers told him stories of "absolutely enormous" specimens. One sketched a stingray in the sand that measured 4 meters wide and twice as long. "He had a tale to match; think sinking boats á la giant squid," Hogan says. But Hogan came away empty-handed.

Letting the cat out of the bag
The plight of the megafishes is beginning to draw more international experts to the area. At a WWF-sponsored meeting on the Mekong giant catfish in Vientiane last month, freshwater scientists and policymakers mulled a fishing ban or limited catch for scientific studies. "We concluded that there is a lack of information to base sound decisions," says WWF's Mollot. Major knowledge gaps include exactly how many giant catfish are caught each year in the Mekong River Basin, where the fish spawn, and whether giant catfish in Cambodian waters in the lower Mekong and fish in the upper reaches of the river are a single population.
   Officials are leaning toward permitting a scientific catch--including taking fin tissue samples for genetic analyses--to get at these questions. "We need rigorous research," says Mollot. At the Vientiane meeting, Lao and Thai officials agreed to forge a common policy for managing the giant catfish. WWF, Mollot says, will also seek to get the species' future "on the table" when policymakers discuss development of the Mekong River Basin.
   They might look to Brazil for guidance. In the Silves region of the Central Brazilian Amazon, indigenous people have set up a zoning system to protect floodplain lakes that are critical to the arapaima and a second imperiled fish, the tambaqui (Colossoma macropomum). Three management regimes are now in place: "sanctuary lakes," nursery grounds where fishing is forbidden; "maintenance lakes," in which only local people can fish, and "open-access lakes." In Lake Purema, declared a sanctuary in the 1980s, Pinho has observed that arapaima are doing better: The average body size of individuals, and the population, are both growing. She is now working with the indigenous people to establish federally protected reserves throughout the country.
   Whether such measures will succeed in the long run will depend largely on community acceptance--and funding. "The problem is that there just isn't much money for protecting these species, or for international fisheries research in general," says Hogan. The Mekong Wetlands Biodiversity Conservation and Sustainable Use Programme kicked in $50,000 for receivers and tags for Hogan's effort before the program was killed last year and its budget redirected for climate change research. NGS is chipping in $35,000 a year for equipment.
   As Science went to press, Hogan, an NGS "emerging explorer," and his Megafishes Project co-director, limnologist Sudeep Chandra of the University of Nevada, Reno, were in Mongolia. There they hope to map critical habitat of the taimen (Hucho taimen), the world's biggest salmon, and ensure that its catch-and-release fishing season is timed to open after spawning. Then Hogan is off to the Amazon--for him, aqua nova--to study the arapaima. "The idea is not to go in and take over arapaima research," he says; it's to get a snapshot of the fish's conservation status. "Zeb tries to involve local scientists," says UBC's Baird. Other megafishes on other continents await Hogan's attention in 2008 and 2009. At the same time, UW's Olden cautions not to lose sight of the smaller picture. "We need to recognize that both the giant and tiny fishes of the world are at risk of global extinction," he says.
   With the threat of extinction growing by the day for some megafishes, Hogan has redoubled his efforts to get the looming catastrophe to resonate with the public. The toughest crowd to reach may be the policymakers who are best positioned to protect the fishes. "There's slow movement forward," says Hogan, who last year was appointed scientific councilor for fish for the U.N. Convention on Migratory Species. "There's not a lot of concern, but there's more concern than there ever has been," he says. This is only the first step on a long road, cautions SUNY's Stewart. "Real solutions will only come from many years of scientific investigation, education, negotiation, legislation, and maybe, in some cases, litigation," he says.
   Some experts say that the battle to save giant fish will be won or lost in the Mekong. "The Mekong represents our last, best chance," argues Dudgeon. Pollution levels on the river are not horrendous, he says, and the lower Mekong still mostly follows its natural flow. Moreover, millions of people depend on the river. Fishery resources "are a part of the cultural fabric of rural life in the Mekong Basin," notes Mollot. Thus for the Mekong giant catfish and other freshwater whoppers, Hogan's success at translating concern into action may mean the difference between a resurgence in the wild and a gloomy existence as the last living representatives of their species. (*1)
   
THE MEGA 20: THE WORLD'S LARGEST FRESHWATER FISH*
CREDITS (TOP TO BOTTOM): COURTESY OF ZEB HOGAN; JEAN-FRANÇOIS HELIAS; SOURCES: ZEB HOGAN; DONALD STEWART; LEANDRO CASTELLO; DAVID DUDGEON; WEI QIWEI; IUCN
COMMON NAME SCIENTIFIC NAME MAXIMUM SIZE FOCAL RIVER SYSTEM IUCN RED LIST
(2006) CATEGORY
MAJOR THREATS
Chinese paddlefish Psephurus gladius 700 cm, 500 kg Yangtze River Basin Critically endangered Harvest, habitat loss
Giant freshwater
stingray
Himantura chaophraya 500 cm, 600 kg Mekong River Basin Vulnerable Harvest, pollution
Wels catfish Silurus glanis 500 cm, 306 kg Widespread in
Europe and Asia
Least concern NA
Arapaima
(pirarucu; paiche)
Arapaima gigas 450 cm, 200 kg Amazon River Basin Data deficient Harvest
Soldatov's catfish Silurus soldatovi 400 cm Amur River Basin Not evaluated Harvest, habitat,
pollution
Piraíba
(laulau; lechero
Brachyplatystoma
filamentosum
360 cm, 200 kg Amazon River Basin Not evaluated Harvest
Alligator gar Atractosteus spatula 305 cm, 137 kg Mississippi River Basin Not evaluated Unknown
Mekong giant catfish Pangasianodon gigas 300 cm, 300 kg Mekong River Basin Critically endangered Harvest, habitat loss
Giant barb Catlocarpio siamensis 300 cm, 300 kg Mekong River Basin Not evaluated Harvest, habitat loss
Giant pangasius
(dog-eating catfish)
Pangasius sanitwongsei 300 cm, 300 kg Mekong River Basin Data deficient Harvest, habitat loss,
pollution
Putitor mahseer Tor putitora 275 cm Brahmaputra River Basin Not evaluated Harvest, habitat loss
Lake sturgeon Acipenser fulvescens 274 cm, 125 kg St. Lawrence, Great Lakes Not evaluated Harvest, habitat loss,
pollution
Wallago
(giant sheatfish)
Wallago attu 240 cm Mekong River Basin Not evaluated Harvest
Mangar Barbus esocinus 230 cm, 136 kg Tigris River Basin Not evaluated Unknown
Mississippi paddlefish Polyodon spathula 221 cm
(including paddle)
Mississippi River Basin Vulnerable Harvest, habitat loss,pollution
Nile perch Lates niloticus 200 cm, 200 kg Nile River Basin Not evaluated Harvest
Pallid sturgeon Scaphirhynchus albus 200 cm, 130 kg Mississippi River Basin Endangered Harvest, habitat loss
Murray cod Maccullochella
peelii peelii
200 cm, 113.5 kg Murray River Basin Not evaluated Harvest, habitat loss
Tanganyika lates
(giant perch)
Lates angustifrons 200 cm, 100 kg Lake Tanganyika Endangered Harvest
Taimen Hucho taimen 200 cm, 100 kg Selenge River Basin,
Lake Baikal, Amur River Basin
Not evaluated Harvest, habitat loss,
pollution
*Excluding sturgeon species that move between freshwater and saltwater.
Threats have been divided into four categories: habitat loss/degradation (associated with agricultural land use, natural resource extraction, and human infrastructure, especially dams); harvesting (for food, medicine, fuel, or materials); invasive species (associated with competition, predation, hybridization, or pathogens/parasites); and pollution (atmosphere, land, or water).
Vulnerable in Australia.


[-back to options at the top(*1)]


Page 2